Caster for baby carriage

ABSTRACT

A caster for a baby carriage  25  is composed of a caster holder  30  mounted to a front leg  12  of a baby carriage  10;  a caster column provided at the caster holder  30  and having a flange shape portion  32   a  at its lower end, and the caster bearing member  36  slidably and rotatably mounted to the caster column  32  and supporting a front wheel  35  at one side. Tapered surfaces  32   b,    36   c  that are inclined toward the circumferential direction and engage each other, are provided on a top surface  32   c  of the flange shape portion  32   a  of the caster column  32  and a downward surface  32   d  of the caster bearing member  36,  respectively. A spring  37  is provided between the caster holder  30  and the caster bearing member  36  to compress the caster bearing member in the direction toward the flange shape portion  32   a  of the caster column  32.

FIELD OF THE INVENTION

[0001] This invention relates to a caster for a baby carriage and more particularly to a caster for a front wheel of a baby carriage.

BACKGROUND OF THE INVENTION

[0002] Baby carriages are generally used to take out babies/children to the outdoors for a walk, shopping, etc. Various baby carriages to easily to fold up, store and carry, are proposed and put in practical use.

[0003]FIG. 11 is a perspective view of a baby carriage that can be folded up as mentioned above. This baby carriage 10 comprises a pair of left and right front legs 12 that have front wheels 11, a pair of left and right rear legs 14 that have rear wheels 13, a hand-pushing rod 15 that is bent to a nearly U-shape, a pair of left and right arm rests 16, and a detachable guard arm 17 that is put over both arm rests 16 and 16. One end of each arm rest 16 is fitted to a portion near the end of left and right pipes 18 of the hand-pushing rod 15 and the top end of each front leg 12 is fitted to the other end of each arm rest 16. The top ends of the left and right rear legs 14 are also fitted to the intermediate portions of the arm rests 16, respectively. One end of a bracket 19 that is bent in a dog leg shape is fitted to the intermediate portion of the rear leg 14. The ends of the left and right pipes 18 of the hand-pushing rod 15 are fitted to the intermediate position of the bracket 19. When the baby carriage is unfolded, lock members 20 installed movably to the lower ends of the pipes 18 engage with the engaging portions formed at the other ends of the brackets 19 and the unfolded state is maintained.

[0004] On the other hand, the left and right front legs 12 are connected with a front side connecting bar 21, and the left and right rear legs 14 are connected with a rear side connecting bar 22. Further, the front end of a connecting bar 23 is fitted to the intermediate portion of the front legs 12 and the rear end of this connecting bar 23 is fitted to the ends of the pipes 18 together with the brackets 19. Further, an upper side connecting bar 24 is connected to the intermediate portions of the left and right connecting bars 23.

[0005] As illustrated in FIG. 11, when the locking members 20 provided at the lower ends of the pipes 18 are engaged with the engaging portions provided at the upper ends of the brackets 19, the baby carriage is held in the usable unfolded state. On the other hand, when the locking members 20 are disengaged from the brackets 19 by operating an operating device 25 provided at the hand-pushing rod 15, the arm rests 16 and the connecting bars 23 become movable upward from the pipes 18 and the connecting points, and the front legs 12 and the rear legs 14 are moved almost in parallel with each other and the baby carriage can be folded up to be easily carried.

[0006] The hand-pushing rod 15, the front side connecting bar 21, the rear side connecting bar 22 and the upper side connecting bar 24 can be folded up by the joints at two points of the intermediate portions in two same vertical surfaces. When the left and right pipes 18 are moved forward after folding up the front legs 12 and the rear legs 14 in the parallel state as described above, the hand-pushing rod 15, the front side connecting bar 21, and the rear side connecting bar 22 and the upper side connecting bar 24 are turned forward and the baby carriage can be folded up more compactly as illustrated in FIG. 12.

[0007] In other words, the baby carriage can be folded into three parts. By the way, casters of a conventional baby carriage are normally used in the state of “Caster Free” to turn around caster columns by 360°. Accordingly, when folding the body of the baby carriage as described above, it is necessary to fold the baby carriage after returning the direction of casters in the straight advancing positions and locking the casters in the straight advancing positions by locking devices.

[0008] However, it is troublesome to operate casters and locking devices with a hand and/or a foot whenever folding the baby carriage. The baby carriage might be so far folded by force without returning the casters to the straight advancing position, thus causing not only breakage of the baby carriage but also a baby carriage looks poor when folded.

SUMMARY OF THE INVENTION

[0009] In view of the points described above, it is an object of this invention to provide a caster for a baby carriage that returns automatically to the straight advancing position from any rotary position when holding a baby carriage body.

[0010] A caster for a baby carriage of the present invention comprises a caster holder; a caster bearing member slidably and rotatably attached to the caster holder; and a wheel provided rotatably to the caster bearing member; and a wheel straight advancing state position fixing device provided between the caster holder and the caster bearing member to return and fix the wheel to the straight advancing position when it is lifted up.

[0011] The caster for a baby carriage of the present invention is characterized in that the wheel straight advancing state position fixing device comprises a caster column provided at the caster holder and has a flange shape portion at the lower end, and a downward surface of the caster bearing member that engages with an upper surface of the flange shape portion.

[0012] The caster for a baby carriage of the present invention is characterized in that the upper surface of the flange shape portion and the downward surface of the caster bearing member are provided with tapered surfaces which are inclined toward the circumferential direction and engage with each other.

[0013] The caster for a baby carriage of the present invention is characterized in that a spring is provided between the caster holder and the caster bearing member to compress the caster bearing member against the flange shape portion of the caster column.

[0014] The caster for a baby carriage of the present invention is characterized in that the tapered surfaces provided on the upper surface of the flange shape portion and the downward surface of the caster bearing member are inclined symmetrically with respect to the longitudinal axes of the baby carriage.

[0015] The caster for a baby carriage of the present invention is characterized in that a cushion material is provided between the caster holder and the spring.

[0016] The caster for baby carriage of the present invention is characterized in that an additional spring is provided between the caster holder and the caster bearing member to serve as a wheel buffer.

[0017] The caster for a baby carriage of the present invention is characterized in that the caster column is formed integrally with the caster holder.

[0018] The caster for a baby carriage of the present invention is characterized in that the wheel straight advancing state position fixing device comprises a caster column that is provided at the caster holder and has a rotary roller attached to the lower end, and the downward surface of the caster bearing member that engages with the roller of the caster column.

[0019] The caster for a baby carriage of the present invention is characterized in that a tapered surface is provided on the downward surface of the caster bearing member, and the tapered surface is in contact with the roller and inclined in the circumferential direction.

[0020] The caster for a baby carriage of the present invention is characterized in that a spring is provided between the caster holder and the caster bearing member to compress the caster bearing member against the roller.

[0021] The caster for a baby carriage of the present invention is characterized in that the tapered surface provided on the downward surface of the caster bearing member is inclined symmetrically with respect to the longitudinal axis of a baby carriage.

[0022] The caster for a baby carriage of the present invention is characterized in that a cushion material is provided between the caster holder and the spring.

[0023] The caster for a baby carriage of the present invention is characterized in that an additional spring is provided between the caster holder and the caster bearing member to serve as a wheel buffer.

[0024] The caster for a baby carriage of the present invention is characterized in that the caster column is formed integrally with the caster holder.

[0025] The caster for a baby carriage of the present invention is characterized in that the wheel straight advancing state position fixing device comprises a fixing pin provided movably outward in the radial direction at the caster bearing member and a concave portion formed extending in the vertical direction on the inner surface of the caster holder for engaging with the fixing pins.

[0026] The caster for a baby carriage of the present invention is characterized in that the fixing pins are compressed outwardly in a radial direction by an elastic member.

[0027] The caster for a baby carriage of the present invention is characterized in that a circumferential groove having upper and lower stepped portions is provided on the outer surface of the caster bearing member, and a stop pin is provided for engaging with the upper and lower stepped portions in the circumferential groove of the caster bearing member.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028]FIG. 1 is a sectional view showing a first embodiment of a caster for a baby carriage of the present invention;

[0029]FIG. 2 is a sectional view showing the grounding state of the caster for a baby carriage shown in FIG. 1;

[0030]FIG. 3 is a diagram for explaining the operation of a caster bearing member;

[0031]FIG. 4 is a sectional view showing a second embodiment of the caster for a baby carriage of the present invention;

[0032]FIG. 5 is a sectional view showing a third embodiment of the caster for a baby carriage of the present invention;

[0033]FIG. 6 is a sectional view showing a fourth embodiment of the caster for a baby carriage of the present invention;

[0034]FIG. 7 is a sectional view showing a fifth embodiment of the caster for a baby carriage of the present invention;

[0035]FIG. 8 is a sectional view showing a sixth embodiment of the caster for a baby carriage of the present invention;

[0036]FIG. 9 is a sectional view showing a seventh embodiment of the caster for a baby carriage of the present invention;

[0037]FIG. 10 is a diagram for explaining the operation of the embodiment shown in FIG. 9;

[0038]FIG. 11 is a perspective view showing a structure of the baby carriage; and

[0039]FIG. 12 is a perspective view showing the folded state of the baby carriage.

PREFERRED EMBODIMENTS

[0040] Hereinafter, the preferred embodiments of the present invention will be described referring to FIG. 1 through FIG. 10.

[0041]FIG. 1 is a sectional view showing a first embodiment of a caster for a baby carriage of the present invention, and in FIG. 1, a caster holder 30 is fixed to the lower end of the front leg of a baby carriage 10 with a rivet 31. The lower half of the caster holder 30 in the vertical direction is bent and the vertical portion of the holder 30 is formed. A column shape space 30 a is formed at the vertical portion of the caster holder 30. The lower end of this space 30 a opens downward. In this space 30 a, a caster column 32 is provided concentrically with the space 30 a and its top portion is inserted into the caster holder 30 and fixed thereto with a rivet 33.

[0042] A caster bearing member 36 supporting a front wheel 35 rotatably by a horizontal shaft 34 is installed to the caster column 32 rotatably around the caster column 32 and slidably between the caster column 32 and the inner surface of the space 30 a of the caster holder 30. At the upper part of the caster bearing member 36, ring shape concave portion 36 a is formed concentrically with the caster column 32. In this ring shape concave portion 36 a, a spring 37 is arranged concentrically with the caster column 32 to compress the caster bearing 36 downward. A washer 38 is provided between the spring 37 and the bottom surface of the ring shape concave portion 36 a of the caster bearing member 36. Further, a cushion 39 with a washer provided on both surfaces of a urethane-like elastic plate is provided between the top wall portion of the space 30 a of the caster holder 30 and the spring 37.

[0043] At the lower end of the caster column 32, a flange shape portion 32 a is formed and this flange shape portion 32 a is arranged in a concave portion 36 b formed on the lower surface of the caster bearing member 36. On a ring shape top surface 32 c of this flange shape portion 32 a, a tapered surface 32 b rising toward the circumferential forward direction is formed symmetrically with respect to a longitudinal the horizontal axis of the flange shape portion 32 a.

[0044] On the other hand, a tapered surface 36 c (FIG. 2) is formed on the downward surface 36 d of the concave portion 36 b of the caster bearing member 36 opposing to the tapered surface 32 b of the flange shape portion 32 a of the caster column 32. That is, the tapered surface 36 c is formed on the downward surface 36 d of the caster bearing member 36 rising in the circumferential forward direction symmetrically with respect to the longitudinal horizontal axis.

[0045]FIG. 2 is a view showing the state of the baby carriage when running, that is, the state of the caster where the front wheel 35 is in contact with the ground. When the front wheel 35 is in contact with the ground, the front leg 12 moves downward by the weight of the baby carriage body. Accordingly, the caster column 32 also moves downward via the caster holder 30 and its flange portion 32 a is projected almost downward from the concave portion 36 b of the caster bearing member 36. Accordingly, the caster bearing member 36 is able to rotate around the caster column 32. When changing the direction of the baby carriage, the caster is able to turn properly and easily change the moving direction. In addition, the vertical vibration caused by the running of the wheel 35 is reduced by the spring 37 and the cushion material 39.

[0046] On the other hand, in the case where the baby carriage 10 is folded up in order to hold and carry it, when the front wheel 35 is lifted up from the ground by lifting the front leg 12 as illustrated in FIG. 1, the caster bearing member 36 is moved downward along the caster column 32 by the spring 37 and the tapered surface 36 c formed on the downward surface 36 d of the caster bearing member 36 in contact with the tapered surface 32 b formed on the upper surface 32 c of the flange shape portion 32 a of the caster column 32. Therefore, the caster bearing member 36 automatically rotates around the caster column 32 until the tapered surface 36 c of the caster bearing member 36 and the tapered surface. 32 b of the caster column 32 are completely fitted and the caster bearing member 36 is fixed at the straight advancing position.

[0047]FIG. 3 is a diagram of the tapered surfaces 36 c, 32 b of the caster bearing member 36 and the caster column 32.

[0048] After the tapered surface 36 c of the caster bearing member 36 and the tapered surface 32 b of the flange shape portion 32 a of the caster column 32 are partially in contact with each other (shown by the solid line), the caster bearing member 36 moves downward while rotating in the direction of an arrow by the inclination of the tapered surfaces 36 c and 32 b and is fixed in the state moved to the position of a one-dot chain line and fixed at the position in FIG. 3. That is, the caster bearing member 36 returns to the straight advancing position automatically and fixed there.

[0049] Accordingly, when folding up the baby carriage 10, it will not be folded by force in the state where the front wheel 35 supported by the caster bearing member 36 is not in the straight advancing position.

[0050] In the construction described above, a wheel straight advancing state position fixing device 26 is composed of the caster column 32 provided at the caster holder 30 and having the flange shape portion 32 a and the downward surface 36 d of the caster bearing member 36 that engages with the upper surface 32 c of the flange shape portion 32 a. Further, this wheel straight advancing state position fixing device 26, the caster holder 30, the caster bearing member 36 and the front wheel 35 comprise the caster for a baby carriage of the present invention.

[0051]FIG. 4 is a view showing a second embodiment of the present invention. In this embodiment, a first spring 40 for pressing and rotating the caster bearing member 36 to the flange shape portion 32 a of the caster column 32 and a second spring (an additional spring) for serving as a buffer of the front wheel are provided and all other elements are the same as those shown in FIG. 1 and FIG. 2.

[0052] In this case, the first spring 40 for rotating the caster bearing member 36 can be a spring having a relatively weak spring force because a load is small, and the second spring 41 can act only after the front wheel 35 is brought in contact with the ground and the flange shape portion 32 a of the caster column 32 is disengaged from the caster bearing member 36. Thus, when moving a baby carriage, the caster bearing member 36 and the flange shape portion 32 a of the caster column 32 are disengaged completely, the direction changing property of the front wheel 35 is not impaired, and traveling efficiency of a baby carriage can be prevented from becoming worse.

[0053]FIG. 5 is a view showing a third embodiment of the present invention. A roller 43 is rotatably attached to a horizontal shaft 42 instead of providing a flange shape portion to the caster column 32. A caster cover 44 is attached to the lower end of the caster column 32 for blocking the opening of the concave portion 36 b of the caster bearing member 36. All others are the same as the embodiment shown in FIG. 1 and FIG. 2.

[0054] In this embodiment, as the roller 43 rotates to the tapered surface 36 c of the caster bearing member 36, the relative movement between the caster column 32 and the caster bearing member 36 is very smooth and an inclined angle of the tapered surface 36 c can be smaller than the first embodiment and the height of the caster bearing member 36 can be smaller accordingly.

[0055] In FIG. 5, the wheel straight advancing state position fixing device 26 is composed of the caster column 32 equipped with the roller 43 and the downward surface 36 d of the caster bearing member 36 that engages with the roller 43.

[0056]FIG. 6 is a view showing a fourth embodiment of the present invention and similarly to that shown in FIG. 4. In FIG. 6, the first spring 40 for rotating the caster bearing member 36 and the second spring 41 for buffering the wheel are provided. Other elements are the same as those shown in FIG. 5.

[0057]FIG. 7 is a view showing a fifth embodiment of the present invention, and the horizontal axis 42 supporting the roller 43 is formed integrally with the caster column 32. In this embodiment, the number of parts can be reduced, compared with those shown in FIG. 5 and the number of assembling steps can be reduced.

[0058] In the embodiments described above, the caster column 32 fixed to the caster holder 30 is shown; however, the caster column 32 may be formed integrally with the caster holder 30 as shown in FIG. 8. In this case, it is not required to fix the caster column 32 to the caster holder 30 and the number of assembling steps can be reduced and the number of parts also can be reduced accordingly.

[0059]FIG. 9 is a view showing a sixth embodiment of the present invention. In the caster holder 30 fixed to the lower end of the front leg 12, a column shape space 30 a whose lower end is opened, is formed. In this space 30 a, a caster bearing member 45 supporting the front wheel 35 by the horizontal axis 34 is mounted so that the cater bearing member 45 can rotate around the axis of the caster bearing member 45 and slide along the inner surface of the space 30 a.

[0060] On the top outer surface of the caster bearing 45, a circumferential groove 46 is provided. A stop pin 47 is provided in the circumferential groove 46 and extends in the horizontal direction. The sliding range in the upper and lower directions of the caster bearing member 45 is defined by engaging this stop pin 47 with the upper and lower stepped portions 46 a, 46 b of the concave portion 46. The caster bearing member 45 is provided with a front straight advancing position fixing pin 48 that is able to move forward/backward in the radial direction of the caster bearing member 45. This pin 48 is compressed so as to project to the outside by a spring 49 mounted in the caster bearing member 45.

[0061] On the other hand, a concave groove 50 is provided at the lower position on the lower inner surface of the space 30 a of the caster holder 30. The front wheel stationary pin 48 is engaged with this groove when the caster bearing member 45 and the front wheel 35 are lowered and the front wheel 35 is set in the straight advancing direction. This concave groove 50 is extending in the axial direction and the upper end portion of the concave groove 50 is inclined toward the inner surface side of the space 30 a of the caster holder 30.

[0062] When the baby carriage is used, the front wheel 35 is in contact with the ground, and therefore the front leg 12 is moved downward, that is, the caster bearing member 45 is at relative higher position with respect to the caster holder 30. Therefore, the front wheel stationary pin 48 is in contact with the inner surface of the space 30 a and therefore able to rotate within the inner surface as shown in FIG. 9.

[0063] On the other hand, when the front wheel 35 is raised upward by the hand-pushing rod when folding the baby carriage, the front wheel 35 moves down by its weight together with the caster bearing member 45 with respect to the caster holder 30. Accordingly, when the front wheel 35 is moved in the straight advancing direction, the front wheel straight advancing position stationary pin 48 is projected by the spring 48, engages with the concave groove 50 and is fixed in the state facing the straight advancing direction. Therefore, the front wheel supported by the caster bearing member 45 is prevented from being folded up by force when it is not in the straight advance position.

[0064] In FIG. 9 and FIG. 10, the wheel straight advancing position fixing device 26 is composed of the fixing pin 48 provided at the caster bearing member 45 and the concave groove 50 formed on the inner surface of the caster holder 30.

[0065] As the caster for a baby carriage caster of the present invention is constructed as described above, when the caster is raised from the ground, the caster bearing member moves automatically from any rotary position to the straight advancing position and is fixed there, and the baby carriage will not be folded with the wheel directed in unspecified direction when folding it. Thus, breakage of the caster is prevented. Furthermore, a troublesome handling such as adjusting the direction of the wheel by hands is not required. In addition, it is not required to provide a locking device for fixing the direction of the wheel, therefore the number of parts can be reduced and the assembling steps of caster can be easier. 

What is claimed is:
 1. A caster for a baby carriage comprising: a caster holder provided to a baby carriage; a caster bearing member attached slidably and rotatably to the caster holder; a wheel provided rotatably to the caster bearing member; and a wheel straight advancing position fixing device provided between the caster holder and the caster bearing member to return and fix the wheel to the straight advancing position when the wheel is lifted up.
 2. The caster for a baby carriage according to claim 1, wherein the wheel straight advancing position fixing device comprises a caster column that is provided at the caster holder and has a flange shape portion at its lower end, and a downward surface of the caster bearing member that engages with an upper surface of the flange shape portion.
 3. The caster for a baby carriage according to claim 2, wherein tapered surfaces are provided on the upper surface of the flange shape portion and the downward surface of the caster bearing member, and these tapered surfaces are inclined in the circumferential direction and engaged with each other.
 4. The caster for a baby carriage according to claim 3, wherein a spring is provided between the caster holder and the caster bearing member to compress the caster bearing member against the flange shape portion of the caster column.
 5. The caster for a baby carriage according to claim 3, wherein the tapered surfaces provided on the upper surface of the flange shape portion and the downward surface of the caster bearing member are inclined symmetrically with respect to the longitudinal axis of the baby carriage, respectively.
 6. The caster for a baby carriage according to claim 4, wherein a cushion material is provided between the caster holder and the spring.
 7. The caster for a baby carriage according to claim 4, wherein an additional spring is provided between the caster holder and the caster bearing member to serve as a wheel buffer.
 8. The caster for a baby carriage according to claim 2, wherein the caster column is formed integrally with the caster holder.
 9. The caster for a baby carriage according to claim 1, wherein the wheel straight advancing position fixing device comprises a caster column that is provided at the caster holder and has a rotary roller mounted at the lower end, and the downward surface of the caster bearing member that engages with the roller of the caster column.
 10. The caster for a baby carriage according to claim 9, wherein a tapered surface is provided on the downward surface of the caster bearing member, and the tapered surface is in contact with the roller and inclined in the circumferential direction.
 11. The caster for a baby carriage according to claim 10, wherein a spring is provided between the caster holder and the caster bearing member to compress the caster bearing member against the roller.
 12. The caster for a baby carriage according to claim 10, wherein the tapered surface provided on the downward surface of the caster bearing member is inclined symmetrically with respect to the longitudinal axis of the baby carriage.
 13. The caster for a baby carriage according to claim 11, wherein a cushion material is provided between the caster holder and the spring.
 14. The caster for a baby carriage according to claim 11, wherein an additional spring is provided between the caster holder and the caster bearing member to serve as a wheel buffer.
 15. The caster for a baby carriage according to claim 9, wherein the caster column is formed integrally with the caster holder.
 16. The caster for a baby carriage according to claim 1, wherein the wheel straight advancing position fixing device comprises a fixing pin provided at the caster bearing member to move forward/backward in the radial direction and a concave groove formed extending vertically on the inner surface of the caster holder with which the fixing pin is engaged.
 17. The caster for a baby carriage according to claim 1, wherein the fixing pin is compressed to the outside in a radial direction by an elastic member.
 18. The caster for a baby carriage according to claim 16, wherein a circumferential groove having upper and lower stepped portions is provided on the outer surface of the caster bearing member, and a stop pin is provided at the caster holder to engage with the upper and lower stepped portions of the circumferential groove of the caster bearing member. 